Electric motor in particular for a steering system in a vehicle

ABSTRACT

An electric motor comprises a stator and a rotor which is rotatably mounted in the stator, the stator having an exciter winding which can be energized via connecting contacts, in a stator housing.  
     The connecting contacts are permanently connected to the stator housing, electrical connecting elements which are accessible from the outside in the radial and axial directions being connected to the connecting contacts.

[0001] The invention relates to an electric motor, in particular for asteering system in a vehicle, according to the preamble of claim 1.

[0002] Such electric motors are composed of a stator having an exciterwinding which can be energized in a stator housing and a rotor which isrotatably mounted in the stator and whose rotor movement is utilized asa working movement. The energization of the exciter winding is usuallycarried out by soldering stranded conductors to the winding ends, whichproject initially out of the stator housing and which can be connectedto connecting cables. In order to be able to transmit the high currentswhich are necessary for high motor powers, high-current plug-inconnectors, via which the winding ends are connected to a control deviceof the electric motor, are used for the electrical connection of theelectric motor.

[0003] However, the currents which are to be transmitted via the plug-inconnectors are generally limited to, for example, 80 Amperes so that itis not possible to generate only very high motor powers with thisconnection technology. On the other hand, it is also not possible todirectly connect the motor lines to the control device owing to thecomparatively complex mounting.

[0004] The invention is based on the problem of forming the exciterwinding of an electric motor in a structurally simple way which permitssimple mounting and a high power drain.

[0005] This problem is achieved according to the invention with thefeatures of claim 1.

[0006] The connecting contacts, which constitute an interface for theelectrical connection to the outside, of the exciter winding arepermanently connected to the stator housing in such a way thatelectrically conductive connection elements which are accessible fromthe outside in the radial and/or axial directions can be connected tothese connecting contacts. The connecting contacts are in particularintegrated into the stator housing, as a result of which a fixed andnonreleasable connection is provided. The winding ends of the exciterwinding, which are arranged within the stator housing, can be connectedto the connecting contacts from the inside. In contrast to the priorart, the connecting contacts form part of the stator housing or areintegrated into it here, as a result of which disruptive movable cableends are dispensed with.

[0007] The connecting contacts are advantageously embodied as clampingelements to which the winding ends are crimped from the inside. Studbolts can be inserted, in particular, screwed into the clamping elementsfrom the outside, it being possible for said stud bolts to be connecteddirectly to a control device on the side facing away from the stator inorder to control the power supply of the electric motor. This controldevice can be connected to the stator housing or to a motor housing intowhich the stator is inserted. The control device is expediently seateddirectly on the stator housing or the motor housing and can bepermanently connected thereto with the result that the control deviceand the electric motor form one structural unit. The stud bolts asconnection elements between the control device and the connectingcontacts of the stator can additionally perform the function ofattachment elements which secure the control device to the motor housingor stator housing.

[0008] In particular if the connecting contacts are arranged on theaxial end side of the stator housing it is possible to provide a covercap which covers the connecting contacts and which protects the contactsagainst soiling. The cover cap can have cutouts through which theconnection elements, in particular the stud bolts, are inserted and canbe connected to the connecting contacts. The cover cap is advantageouslylocated in a common outer casing surface with the stator housing, whichmakes it easier to insert the stator axially into a radial inner spaceof a motor housing.

[0009] Further advantages and expedient embodiments can be found in thefurther claims, the description of the figures and the drawings. Of saiddrawings:

[0010]FIG. 1 shows a section through an electric motor with a statorwhich is accommodated in a motor housing, and a rotor which is mountedin the stator, connecting contacts which are connected via stud bolts toa control device located on the top being provided in the region of theaxial end side of the stator,

[0011]FIG. 2 shows a perspective view of the stator with connectingcontacts arranged on the axial end side of the stator housing,

[0012]FIG. 3 shows a partial view of a longitudinal section through theelectric motor with the control device located on the top,

[0013]FIG. 4 shows a perspective view of a cover cap which can be fittedaxially onto the connecting contacts.

[0014] Identical components are provided with identical referencesymbols in the following figures.

[0015] The electric motor 1 which is illustrated in FIG. 1 is inparticular a three-phase asynchronous motor which is advantageously usedto support the steering movement in the steering system of a vehicle.The electric motor 1 comprises, in a motor housing 2, a stator 3,composed of a stator housing 4 and an exciter winding which is arrangedon the stator housing 4, as well as a rotor 5 which is rotatably mountedin the stator 3 and whose rotary movement is exploited as a workingmovement. The stator 3 is of cylindrical design and is inserted into acorresponding shape cutout in the motor housing 2. In order to securethe stator 3 in the motor housing 2, it is possible to provide axiallyextending attachment elements 7 which bring about in particularsecurement with respect to rotation, but also possibly axial securementof the stator 3 in the motor housing 2.

[0016] On the upper side of the motor housing 2 there is a controldevice 6 which is in particular permanently connected to the motorhousing 2 and by means of which the power supply and control for theexciter winding in the stator 3 is carried out.

[0017] The connection between the exciter winding in the stator 3 andthe power supply and power control is carried out by means of thecontrol device 6 via a total of three connecting contacts which areembodied as clamping elements 8 and to which the winding ends of theexciter winding are crimped. The clamping elements 8 are located on theaxial end side of the stator housing 4 of the stator 3 and are inparticular permanently connected to the stator housing 4. The clampingelements 8 are advantageously composed of copper and can be cast intothe stator housing 4 which is expediently composed of plastic. Eachclamping element 8 has an internal thread into which a stud bolt 9 isscrewed, which stud bolt 9 has the function of a connection element forconnecting the exciter winding to the control device 6. The stud bolt 9performs both an electrically conductive function and a securing,clamping and connecting function in order to connect the control device6 to the motor housing 2. The total of three stud bolts 9 are readessentially radially through the motor housing 2 which engages aroundthe stator 3, and are inserted into the clamping elements 8. All threestud bolts 9 are located parallel with one another. The stud bolts 9connect the stator housing 4, motor housing 2 and control device 6.

[0018]FIG. 2 shows a perspective view of the stator 3 with the clampingelements B which are attached at the end side to the stator housing 4and are covered by a cover cap 11 which can be fitted axiallydisplaceably onto the clamping elements 8. The cover cap 11, which iscomposed in particular of plastic and which protects the clampingelements against soiling as well as having an insulating effect, hascutouts which are matched to the clamping elements 8 and are radiallyaccessible so that the clamping elements B are radially accessible fromthe outside even when the cover cap 11 is fitted on, and the stud boltswhich are illustrated in FIG. 1 can be screwed in. The radiallyoutermost casing surface of the cover cap 11 is essentially congruentwith the radial outer casing surface of the stator housing 4.

[0019]FIG. 2 also shows the exciter winding 10 within the stator housing4.

[0020] As illustrated in FIG. 3, the clamping elements 8 are located onthe axial end side of the stator 3 and the motor housing 2 engages overthem axially. The stud bolts 9 are led through a cutout in the controldevice 6, which is attached to the motor housing 2, and are cutout inthe motor housing, and screwed into the clamping elements B.

[0021]FIG. 4 illustrates the cover cap 11 in isolation. The radiallyouter casing surface of the cover cap 11 is curved and has a radiuswhich corresponds essentially to the radius of the stator housing of thestator. A total of three cutouts, in which the clamping elements B areheld in the installation position, is provided in the cover cap 11. Thecutouts 12 are accessible both axially and radially, the axial openingscorresponding to the shape of the clamping elements so that the covercap 11 can be fitted axially onto the clamping elements, whereas theradial openings in the cross section are of round design and have apurpose of accommodating the stud bolts.

List of Reference Numerals

[0022]1 Electric motor

[0023]2 Motor housing

[0024]3 Stator

[0025]4 Stator housing

[0026]5 Rotor

[0027]6 Control device

[0028]7 Attachment element

[0029]8 Clamping element

[0030]9 Stud bolt

[0031]10 Exciter winding

[0032]11 Cover cap

[0033]12 Cutout

1. An electric motor, in particular for a steering system in a vehicle,having a stator (3) and a rotor which is rotatably mounted in thestator, the stator (3) having an exciter winding which can be energizedvia connecting contacts, in a stator housing, characterized in that theconnecting contacts are permanently connected to the stator housing (4),it being possible for electrical connection elements which areaccessible from the outside in the radial and axial directions to beconnected to the connecting contacts.
 2. The electric motor as claimedin claim 1, characterized in that the connecting contacts are arrangedon the axial end side of the stator housing (4) and are radiallyaccessible from the outside.
 3. The electric motor as claimed in claim 1or 2, characterized in that the connecting contacts are embodied asclamping elements (8).
 4. The electric motor as claimed in claim 3,characterized in that stud bolts (9) which can be inserted into theclamping elements (8) are provided as connection elements.
 5. Theelectric motor as claimed in one of claims 1 to 4, characterized in thatthe stator (3) can be inserted into a motor housing (2), the connectingcontacts being accessible from the outside through radial openings inthe motor housing (2).
 6. The electric motor as claimed in one of claims1 to 5, characterized in that the connection elements which are to beconnected to the connecting contacts project, on the side facing awayfrom the connecting contacts, into a control device (6) which isconnected to the stator housing (4).
 7. The electric motor as claimed inone of claims 1 to 6, characterized in that a cover cap (11) whichcovers the connecting contacts is provided.
 8. The electric motor asclaimed in one of claims 1 to 7, characterized in that the electricmotor is a three-phase asynchronous motor.